In yeast and mammalian cells, artificial chromosomes have been used to investigate the role of centromere DNA in chromosome inheritance. In human and mouse cell lines, these studies demonstrated a requirement for repetitive DNA; yet it remains difficult to predict which repeats will provide autonomous chromosome maintenance throughout the tissues of an organism. The immediate goal of this research is to develop a rapid, cost-effective and high throughput mini-chromosome system that tests centromere sequence function in cells, tissues and whole organisms. Plants are ideal for this effort-i) their centromere DNA is organized in arrays similar to those of mammals; ii) they can be transformed in large numbers; iii) they can be regenerated from individual somatic cells; iv) they produce gametes from multiple independent cell lineages, making it possible to analyze mitotic and meiotic chromosome transmission in sectors; and v) they are tolerant of aneuploidy, facilitating the introduction of additional chromosomes. The proposed research will characterize circular and linear mini-chromosome constructs in plant cells, monitoring their inheritance, capacity for gene expression, and structural integrity. The long-term, Phase III goals are to engineer these mini-chromosomes to use plants to produce products important for human health, such as vaccines, pharmaceuticals, or neutraceuticals. [unreadable] [unreadable]